Historically, access to certain secure areas, including offices, buildings, etc., was controlled using mechanical devices, such as keys, and the like. Advances in field of electronic security provided means of accessing secure areas using electronic devices, such as electric badges, fobs, etc. These electronic devices store an access code. When an electronic signal with a query is received by each device, each device responds with the access code. A security system (which normally generates the initial signal with the query) analyzes the access code received from a particular electronic device, and if the access code is acceptable, the user associated with the respective device is allowed access to the secure area, for example by opening a gate.
Such electronic devices have several distinct advantages for the users and the respective security units desiring to control the access. For example, electronic access devices can be smaller and lighter then mechanical keys and, therefore, can be carried easily.
From the security unit's point of view, electronic devices are advantageous because they are harder to duplicate then mechanical keys. Moreover, electronic devices can be used with sophisticated systems to control and/or keep track of who can access a secure area and when. For example, a security system can be set up to allow access to a first group of users at during one particular time period (e.g., weekday mornings), a second group of users at another particular time period (e.g., weekends), etc. Access to a particular secure area by a particular user may also be suspended or terminated by the security unit without the need to obtain the electronic device from the user.
A disadvantage of electronic devices of the kind just described is that they still must be carried separately, just like the old mechanical keys.